Spark-plug.



B. A. JEFFERY SPARK PLUG.

Patented July 3, 1917.

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BENJAMIN A: JEFFERY, OF DETROIT, MICHIGAN.

' SPARK-PLUG.

Specification of Letters Patent.

Patented July 3, 1917.

- Application filed December 9, 1913. Serial No. 805,569.

To all whom it may concern:

Be it known that I, BENJAMIN A. JEF- rnRr, a citizen of the UnitedStates, residing at Detroit, in the county of Wayne and State ofMichigan, have invented new and useful Improvements in Spark-Plugs, ofwhich the following is a specification.

This invention relates to an improved spark plug.

One of the objects of the invention is to provide improved means forsupporting the insulating block of a spark plug. A further object is toprovide means for maintaining a tight joint between the insulating blockand a supporting element connected therewith, whereby the separatinginfluences of the pressure of the fluids or gases to be retained, areresisted. A further object is to provide means by which the initialstrains to be placed upon the porcelain insulating block for the purposeof securing a tight joint, may be predetermined and regulated. A furtherobject is to provide an improved packing between the porcelaininsulating block andits'supporting bushing, said acking havingsubstantially the same coe cient of expansion as the material formingsaid insulating block. A further object is to provide means forpreventing torsional or other strains, on the insulating block, whichmanipulation of the securing bushing might set up. A further object isto provide means for reinforcing the insulating block.

The invention will be hereinafter fully set forth and particularlypointed out in the claims. I

In the accompanying drawings Figure 1 is a longitudinal sectional viewof a spark plug constructed in accordance with my invention. Fig. 2 is asimilar-view of a slight modification. Figs. 3 and 4 are opposite endviews. Fig. 5 is a detail view illustrating the ferrule.

Referring to the drawing, 10 designates a shell provided with the usualscrew threads 11 for engagement with the engine casing. Said shell isprovided with a longitudinally tapered bore 12 provided with an annularshoulder-2.13, the upper portion of the bore being screw threaded, asindicated at 14:.

The threaded portion 14 is arranged to engage a correspondingly threadedportion of the usual bushing 15.

The insulating block 16 is made of suit.- able material, preferablyporcelain, and

a ferrule 22, the edges of which are bent over the respective flanges toprevent separation thereof. It will be noted that the bushing 15 isprovided with a bore to receive the insulating block and collar 19, saidbore being large enough .to provide a slight radial clearance for the.packing. The bore 12 of the shell 10 is large enough to provide 'aslight radial clearance for the packing ring 20. Likewise, that part ofthe shell which incloses the flanges 21 also provides radial clearancefor said' flanges and the ferrule which surrounds them.

In practice the parts are assembled in the following manner :The packingcollars 19, 20 are forced, from opposite ends, longitudinally on to thedouble cone or tapered portions 17, 18, until the flanges meet. Theferrule is then put over the flanged portions of the two packingcollars, being in the form illustrated in Fig. 5, and the open endturned inwardly, thus causing the ferrule to envelop the three exposedsurfaces of the flanges 21. The flanges and ferrule thus form a rigidnon-yieldable supporting member of tubular form to engage and sustainthe insulating block, and having a flange midway of its ends, whereby itmay be supported. The porcelain with the two continuous contact ispossible; and second,

by bringing these surfaces together with sufficient force to resist theseparating influblock and also by providing suflicient area of crosssection in the parts to furnish the necessary strength. An alloy of thecharacter referred to is described in Letters Patent 626,609.

The insulating block 16 is provided with a central electrode 25 embeddedtherein provided with a sparkingpoint 26 cooperating with a groundedelectrode 27 carried by the shell'10. The electrode 25 is also providedat its other; end with a binding post 28 of any suitable or preferredconstruction.

In Fig. 2 I have illustrated a slight modification, which consistsprincipally in dispensing with the bushing 15 by means of which theinsulating block is removably supported by the shell 10, andsubstituting therefor a ring or spacing piece 29 which rests upon theflange 21. This collar is forced. longitudinally toward the shoulder 13,by crimping over the thin edge 30 on the upper portion of the shell,enough pres sure being exerted to force the lower face of the flange 21into a gas tight joint with he the shoulder 13. It will be understoodthat art .to which it appertains.

in this form of the invention a slight radial clearance is pr videdbetween the flange 21 and the bore O F thG shell is provided.

The advantages of my invention will be readily understood by thoseskilled in the the constructions herein illustrated and described, thestrain, which might be called the initial strain to be put upon theporcelain insulating block for Q16 purpose of securing a tight 3' o1nt,can be predetermined and regu-v lated by the relative sizes of the boresof the packing collars and the shoulderof the porcelain itself; also thethickness of the metal in the packing collar, to give only so muchresistance to leakage and mechanical strains as is necessary to preventthe former and keep the latter from causing any disarrangement of theparts of the plug. By means of my invention, also, any torsionalstraining of the porcelain insulating block, such as could be caused bythe tendency of one packing collar to twist in relation to the other,were the bushing to screw down directly onto the upper packing collar,is prevented by the use of the ferrule'which takes this strain. Saidferrule being made of soft metal-acts as a gasket between the lower Bymeans of.

packing flange and the internal shoulder in the shell. The use of theform of packing ring herein described results in a very great increasein the effective strength of the porcelain, both on account of theelimination of unnecessary strains and the reinforcement afforded by theextension of the packing collar above the usual point of support, asmore fully appears in the form illustrated in Fig. 2.

Having thus explained the nature of my invention, and described anoperative manner of constructing and using the same, although withoutattempting to set forth all of the forms in which it may be made, or allof the modes of its use, what I claim 1s:

1. An improvement in spark plugs comprising a supporting shell, aninsulating block provided with an electrode, rigid pacl ing having atubular portion surrounding said block and having an inseparablefrictional engagement therewith, the periphery of said packing beingprovided with a rigid unyielding annular portionintermediate of the endsof the tubular portion for supporting the insulating block within theshell, means engaging said flange to retain the insulating block withinthe shell, and a second electrode carried by the shell.

2. An improvement in spark plugs comprising a supporting shell, aninsulating block provided with an electrode, oppositely disposedindependent packing collars connected with said insulating block andprovided with rigid unyielding abutting portions supporting the latterwithin said shell, and a second electrode carried by said shell.

3. An improvement in spark plugs comprising a supporting shell, aninsulating block provided with an electrode, oppositely disposedindependent packing collars con nected with said insulating block andprovided with. rigid unyielding abutting portions supporting the latterwithin said shell, means enga 'ng said collars to retain said insulatingb ock within said shell, and a second electrode carried by said shell.

4. An'improvement in spark plugs comprising a supporting shell, aninsulating block provided with oppositely tapered surfaces,- anelectrode within said block, oppo-. sitely disposed packing collarsforced upon the respective tapered surfaces of said 'insulating blockand provided with abutting annular flanges for supporting saidinsulating block, and a second electrode carried by said shell.

t An improvement in s ark plugs comprising a supporting she aninsulating block provided with oppositely tapered surnaaaose annularflanges for supporting said insulating block, a ferrule uniting saidflanges, and a second electrode carried by said shell.

6. An improvement in spark plugs comprising a supporting shell, aninsulating block provided with oppositely tapered surfaces, an electrodewithin said block, oppositely disposed packing collars forced upon therespective tapered surfaces of said insulating block and provided withabutting annular flanges for supporting said insulating block, meansengaging said flanges to retain the insulating block within said shell,and a second electrode carried by said shell.

7. An improvement in sparkplugs comprising a supporting shell, aninsulating block provided with oppositely tapered surfaces, an electrodewithin said block, oppositely disposed packing collars forced upon therespective tapered surfaces of said insulating block and provided withabutting annular flanges for supporting said insulating block Withinsaid shell, a ferrule uniting said flanges, a bushing engaging saidshell and said ferrule to retain said insulating block within saidshell, and a second electrode carried by said shell.

@An improvement in spark plugs comprising a supporting shell, aninsulating" block provided with oppositely tapered exterior surfaces,oppositelydisposed packing collars forced upon the respective taperedsurfaces, means engaging said packing to retain said insulating blockWithin said shell, and electrodes carried by said insulating block andsaid shell, respectively.

9. An improvement in spark plugs comprising a supporting shell, aninsulating block provided with oppositely tapered exterior surfaces,oppositely disposed packing collars forced upon the respective taperedsurfaces and provided with abutting annular flanges, means engaging saidflanges to retain said insulating block within said shell, andelectrodes carried by said insulating block and said shell,respectively.

10. As an improvement in spark plugs, an

insulating block provided with a central insulating block provided withan electrode and having exterior packing collars secured thereto andprovided with abutting flanges, and a ferrule uniting said flanges, saidcol lars having the same coeflicient of expansion as said insulatingblock.

18. As an improvement in spark plugs an insulating block provided withan electrode and having exterior oppositely tapered surfaces, abuttingpacking collars having an inseparable frictional engagement with saidsurfaces, and means for uniting said packing collars, said collarshaving the same co efficient of expansion as said insulating block.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

BENJAMlN A. JEFFERY.

Witnesses:

JOSEPH ARTHUR JEFFERY, FRED. L. PARKER.

